Fix BcMath\Number unary plus/minus

Author: mpesari

src/Type/ObjectType.php

@@ -762,6 +762,10 @@ public function toNumber(): Type
 			]);
 		}
 
+		if ($this->isInstanceOf('BcMath\Number')->yes()) {
+			return $this;
+		}
+
 		return new ErrorType();
 	}
 

tests/PHPStan/Analyser/nsrt/bcmath-number.php

@@ -408,8 +408,8 @@ public function bcVsNever(Number $a): void
 
 	public function bcUnaryOp(Number $a): void
 	{
-		assertType('*ERROR*', +$a);
-		assertType('*ERROR*', -$a);
+		assertType('BcMath\Number', +$a);
+		assertType('BcMath\Number', -$a);
 		assertType('*ERROR*', ~$a);
 	}
 

tests/PHPStan/Rules/Operators/InvalidUnaryOperationRuleTest.php

@@ -173,14 +173,6 @@ public function testUnion(): void
 	public function testBcMathNumber(): void
 	{
 		$this->analyse([__DIR__ . '/data/unary-bcmath-number.php'], [
-			[
-				'Unary operation "+" on BcMath\Number results in an error.',
-				9,
-			],
-			[
-				'Unary operation "-" on BcMath\Number results in an error.',
-				10,
-			],
 			[
 				'Unary operation "~" on BcMath\Number results in an error.',
 				11,